LAUSR

ABSTRACT The aim of this study was to assess the changes in soil organic carbon (SOC) stock in relation to the carbon (C) input from nine wheat-based cropping systems and untilled grass. The SOC pool ranged from 32.1 to 49.4 Mg ha−1 at 0–20 cm and from 94 to 171 Mg ha−1 at 0–100 cm for the arable soil, while in untilled grassland, it was higher (54 and 185 Mg C ha−1, respectively). SOC stock was observed to be lower at the unfertilized 2-year rotation and higher at the 4-year rotation with manure and mineral fertilization. The study showed a winter wheat yield decrease of 176.8 kg ha−1 for a 1- Mg ha−1 SOC stock change in the 0–20-cm soil depth. The estimated C input for SOC stock maintenance was from 266 to 340 g C m−2 year−1 for winter wheat and rotations, respectively. Additional C input did not increase the SOC pool, suggesting that arable plots had a limited ability to increase SOC. These results provide guidance for the selection of management practices to improve C sequestration.